Manhole openings are used to provide access to most underground facilities such as sanitary sewers and storm drains, utility conduits, etc. Such manhole openings, often located in the street or roadway, are covered by a manhole cover which is supported by a frame, typically made of metal, that is mounted on top of a concrete conduit or concrete riser. Thus, access to sewers or utility components is possible when the cover is removed from the support frame assembly, thereby allowing access to the lower structure and a subterranean conduit network interconnecting such concrete risers.
In known multi-component manhole assemblies, an adjustment riser is often disposed between the lower structure, for example the concrete riser, and the frame assembly within which the cover is supported. These adjustment risers have two functions, first they occupy the gap between the lower structure and the frame assembly to complete the assembly of the manhole or catch basin hole, and secondly they absorb mechanical vibrations developed above the frame assembly, such as by vehicles travelling over the metal cover when the hole is located in a road, and inhibit transmission of the mechanical vibrations to the lower structure. However, in circumstances when there is an angle or camber in the roadway and there is thus a need to be able install the manhole frame, and thus the cover, at a particular angle relative to the fixed concrete risers, existing risers have not proved sufficient to adequately control and modify an installation angle of the manhole cover as may be required. The use of known adjustment risers between the concrete base structure and the manhole frame, while advantageous for vibration damping, can make angular adjustment of the frame and cover, relative to the underlying concrete riser, difficult.
The covers of such known multi-component manhole assemblies typically have holes therethrough or do not seal well within their supporting frame, and therefore permit water ingress into the manhole. Therefore, known systems often include an inflow insert or catch basin which is provided beneath the manhole cover for the purposes of catching and collecting water inflow. Such catch basins need to be emptied on a fairly regular basis, which is clearly undesirable.
Additionally, the component parts of known manhole or catch basin assemblies are typically manufactured at poor manufacturing precision, such that a cover or closure member in which is the uppermost component is located generally flush with an exposed paved surface such as a road surface, fits poorly in the manhole or catch basin assembly and thus many gaps exist through which water ingress is possible. The other components of the assembly also tend to poorly fit and have gaps which provide a path for flow of water throughout the assembly structure.
As noted above, water inflow inserts provided beneath the cover of existing manhole assemblies for the purposes of collecting and/or redirecting rainwater, have been found to be insufficient for installations wherein a watertight access cover may be required. For example, subterranean vaults for electronics and/or telecommunications equipment, etc, need to be adequately sealed form the elements while still permitting access thereto via a manhole cover. It would be desirable to be able to prevent water from being able to flow through such manhole openings in order as to prevent any water ingress into such sensitive subterranean conduits and vaults.